1. Field of the Invention
The present invention relates generally to devices for imprinting fixed and variable information on business forms and similar documents, and is particularly concerned with an improved digit wheel assembly for use in connection with devices of this nature. The invention also embraces an improved cantilever-type imprinter head configuration which permits oversized forms to be accommodated by the imprinting device.
2. Description of the Prior Art
Imprinting devices for transferring to a printed form the fixed and variable information relating to a business transaction are well known and have been in general use in various types of retail establishments for many years. Typically, the purchaser presents the retailer with a plastic credit or charge card, upon which are embossed the customer's name, address, account number, and other pertinent information in raised letters. The retailer places the card, together with a prepared form containing one or more carbon duplicates, into the imprinting device. In the imprinting device, a platen roller is rolled over the card and prepared form in order to transfer a printed image of the information on the card to the form. Generally, the imprinter also includes a permanently-affixed metal plate (sometimes referred to as the "merchant plate") containing the name and address of the retail establishment in raised lettering, so that this information is transferred to the form at the same time.
In the simplest types of imprinters, the foregoing "fixed" type of information (plus, in some cases, the form by the imprinter. The remaining "variable" information, such as the price of the goods or services purchased, the applicable taxes, and so on, must then be added to the form manually. This is not only inconvenient at the point of sale, but also makes it difficult or impossible to process the forms automatically using optical character recognition equipment. As a result, each form must be clerically read and keyed into a computer at the processing center before the purchaser can be billed. This, of course, is both time-consuming and susceptible to errors.
In an effort to overcome these disadvantages, the so-called "variable imprinter" has been developed. In this type of imprinter, the variable information (i.e., that information which will normally change for each successive transaction, such as the total amount of the sale) is preset on the machine before the imprinting operation is carried out, and is transferred to the prepared form at the same time as the customer's account information and the name and location of the retail establishment is transferred. This is usually done by means of an adjustable set of digit wheels which are in one way or another brought into contact with the form during the imprinting operation. A common arrangement is to install the digit wheel assembly within the imprinter housing so that it protrudes slightly through a slot or cut-out in the print bed. Adjustment of the digit wheel settings is usually accomplished by means of sliding gear racks which cooperate with gear teeth formed on the sides of the individual digit wheels. The gear racks, in turn, are usually moved by a set of slidable tabulator keys which are received in long slots on the front panel of the imprinter. Imprinting machines of this general type are disclosed, for example, in U.S. Pat. Nos. 3,138,091 and 3,521,556.
Although variable imprinters constructed along the foregoing lines have enjoyed significant commercial success, numerous problems still remain. Not the least of these has to do with the rack-and-pinion system used for setting the digit wheels, which is a rather cumbersome arrangement from the standpoint of manufacture as well as operation. The gear racks, in particular, are rather large special-purpose metal parts which are expensive to manufacture, and which therefore add significantly to the cost (and weight) of the finished unit. In addition, the necessary length of the gear racks tends to render imprinters of this type rather large in overall dimensions, which is a distinct disadvantage in retail establishments where counter space is at a premium. A further disadvantage of the rack-and-pinion adjustment, albeit perhaps of a more subjective nature, has to do with the significant degree of sliding friction that is inherent in mechanical arrangements of this sort. As a result of this, imprinters of the rack-and-pinion type tend to have a rather coarse "feel" from the standpoint of the effort required to make the required adjustments.
A further poblem that has not been adequately solved in presently available imprinting machines has to do with the sizes of forms that these machines will accept. Conventional "flatbed" type imprinters, in which the platen rollers are contained in a movable imprinter head that is supported by rollers at two edges of the imprinter unit, are usually capable of accepting only certain size forms, such as the usual 51- and 80-column credit card form sheets. Larger-size forms, such as a standard cash register form, cannot be accommodated. For this reason, it is common for retailers to have on hand a second imprinter of the "open head" type. In this type of unit, the imprinter head is operated by means of a plunger-type handle and is attached to the base of the unit by means of a hinge, which allows the imprinter head to be pivoted away from the base in order to accommodate the larger form. Open head imprinters are generally more expensive than the flatbed units, however, and the print quality produced by open head machines is often not as good as that produced by flatbed machines. These factors tend to make open head units unattractive to retailers despite the added versatility they provide.